This invention relates to tool holders and more particularly, to tool holders adapted releasably to hold a disposable cutting insert in a seat or recess formed in the shank thereof.
Cutting tools of the aforesaid type typically have three or in some instances four, components--a shank, a retention pin, a disposable cutting insert made of a very hard cutting material such as a suitable metallic carbide, and if necessary, a seat or seating member for the insert. The shank is formed with a recess to provide a seating face and a supporting shoulder for the insert or for the insert and the seating member. The retention pin is typically adjustably secured at one end thereof in a threaded bore formed in the shank. The other end of the pin projects into a hole in the insert. The design of the assemblage is such that as the retention pin is threaded into the bore in the shank, it forces the cutting insert against the supporting shoulder of the shank and locks it in operating position.
Representative patents disclosing tool holders of this type are as follows:
U.S. Pat. No. 3,533,150, Welch, discloses a retention pin which when fully seated, translates axially to cause the head portion thereof the force the cutter insert into snug engagement with the shoulder. U.S. Pat. No. 3,097,417, Hill, discloses a tool holder wherein the retention pin has an eccentrically positioned head portion, whereby rotation of the pin causes the head portion to force an insert against a supporting shoulder.
The following patents utilize retention pins having frusto-conical or wedging portions to force a cutting insert against a supporting shoulder: U.S. Pat. No. 3,284,874, Green et al; U.S. Pat. No. 3,310,859, Diemond et al; U.S. Pat. No. 3,341,919, Lovendahl; U.S. Pat. No. 3,613,198, Weber.
U.S. Pat. No. 3,341,920, Kelm, discloses a retention pin which acts as a lever with its fulcrum at its lower or threaded end, laterally to displace its head portion toward a locking shoulder to secure a cutter insert in place. U.S. Pat. No. 3,654,682, Newbould, discloses a retention pin which provides a fulcrum intermediate its ends to force a cutter insert against a shoulder of a recess in the shank.
A principal object of the present invention is to provide a cutting tool of the aforesaid type wherein the retention pin is simpler in design and accordingly, less expensive to fabricate.
A further object of the present invention is to provide a cutting tool of the aforementioned type wherein the bore in the shank has but one axis and thus, requires only one drilling and tapping operation.
A still further object of the present invention is to provide a cutting tool of the aforementioned type wherein the retention pin will tip instead of just laterally translate as it seats the cutter insert snugly against the shoulder of the recess in the shank.
A still further object of the present invention is to provide a cutter tool wherein a retention pin is fabricated from a blank having a cylindrical head portion which initially, is coaxially disposed with respect to the cylindrical body portion of the pin prior to any threading thereof.
A still further object of the invention is to provide a cutter tool which will prevent the cutter insert from tipping when it is forced into its operating position.